Conventionally, for a surface-protective film and an interlayer insulating film of a semiconductor device, a polyimide having, in combination, excellent heat resistance, electrical properties, mechanical properties or the like has been used. In recent years, a photosensitive polyimide obtained by providing a polyimide itself with photosensitive properties has been used. By using such a photosensitive polyimide, there are advantages that pattern-forming steps can be simplified, whereby a complicated production steps can be shortened.
For developing a photosensitive polyimide, an organic solvent such as N-methylpyrrolidone has been used. In recent years, in respect of environment protection, a positive-type photosensitive polyimide which can be developed with an aqueous alkaline solution has been proposed. As a method for forming a positive-type photosensitive polyimide, a method in which a naphthoquinone diazide compound as a photosensitizing agent is mixed with a polyimide or a polyimide precursor has been proposed (see Patent Documents 1 and 2, for example).
Further, recently, as a positive-type photosensitive resin which can be developed by an aqueous alkaline solution, polybenzoxazole or a polybenzoxazole precursor has been proposed. As compared with a polyimide or a polyimide precursor, polybenzoxazole or a polybenzoxazole precursor has a large difference in dissolution speed between an exposed part and un-exposed part, and hence, a more precise pattern can be formed (see Patent Document 3, Non-Patent Document 1, for example).